Communications 1/Fundamentals of Communications

Identify the type of modulation where the frequency of the modulated wave is equal to that of the carrier wave.

• Frequency modulation

• Amplitude modulation

• Carrier modulation

• Phase modulation

What does AGC stand for?

• Automatic gain control

• Automatic gear control

• Amplitude gain control

• Automotive gear center

Why is AM used for broadcasting in the communication systems?

• Its use avoids receiver complexity

• It is more immune to other modulation systems

• It requires less transmitting power

• No noise disturbances

Of the following which is the preferred modulation scheme for digital communication?

• Pulse code modulation

• Pulse amplitude modulation

• Pulse position modulation

• Pulse width modulation

A carrier of peak voltage 15 V is used to transmit a message signal. If the modulation index is 70%, then what will be the peak voltage of the modulating signal?

• 25 V

• 11 V

• 10.5 V

• 30 V

PAM stands for pulse attenuation modulation.

• True

• False

‘X’ for an AM is the ratio of change in amplitude of the carrier wave to the amplitude of the original carrier wave. Identify ‘X’.

• Automatic gain control

• Modulation index

• Phase index

• Amplitude index

How can the noise be reduced in AM signal?

• Increasing amplitude

• Increasing wavelength

• Increasing bandwidth

• Increasing frequency deviation

Suggest a possible communication channel for the transmission of a message signal that has a bandwidth of 200kHz.

• TV transmission

• Optical fiber

• AM radio

• FM radio

Identify the type of modulation where the modulating wave is superimposed on a high-frequency carrier wave.

• Phase modulation

• Amplitude modulation

• Frequency modulation

• Wavelength modulation